Jeans and leggins to me sound like the most uncomfortable thing in the world, ESPECIALLY skinny jeans.
In my opinion sweatpants ALWAYS look sloppy. They can be as nice as you want but they're sweat pants. Save them for relaxing around the house, cold days and the gym if you want to look nice. They're casual but they're not presentable or nice.
My comfy casual wear is a nice, clean looking pair of loose cargo pants and some kind of fitting light cotton long sleeve shirt. Or, a nice short sleeve shirt with a long sleeve on under it. And, most importantly, a warm, soft sweat shirt. Nothing more comfy than that.
Jeggings. Those things are amazing - they look exactly like jeans (at least the ones I get, I buy the Bullhead ones from PacSun) but are reallly comfortable. Alternately, leggings are good if you wear a looser shirt or sweater that covers your butt. Oversized pullovers and V-necks are really comfortable.
And personally, I think dresses and skirts are really comfortable as well, especially when it's hot out. A casual dress made out of cotton or something (that's not too tight) is THE most comfy thing to wear, ever.
And shoes-wise, moccasins and slip-ons are really comfy.